SPF (Sender Policy Framework)
01 Definition
SPF (Sender Policy Framework) meaning: An email standard listing which servers are allowed to send mail for a domain.
SPF, or Sender Policy Framework, is a DNS record that names the servers and IP addresses authorized to send email for a domain. The receiving server checks the sending IP against this list. SPF alone does not stop spoofing of the visible From address, so it works alongside DKIM and DMARC.
Why it matters
How SPF (Sender Policy Framework) fits the work
SPF lets receivers verify that mail claiming to come from your domain was sent by a server you approved, a basic defense against forgery and a requirement for many inboxes.
In context
The admin added the ESP's servers to the domain's SPF record so bulk campaigns would pass authentication at Gmail and Outlook.
Practical note
SPF checks the hidden envelope sender, not the visible From address, and it breaks when mail is forwarded, which is why DMARC also relies on DKIM alignment.